Speed or mileage?

Quick question: what is better for a beginner, increase the mileage or the speed of running? I'm getting comfortable at running 5k almost everyday but I am dead slow (9-10mins/km, more one my worst days). I'm thinking in increasing my speed first for the 5K and then gradually add some more ks, but I would love your thoughts/experiences on this.

I went the mileage route for the last two years, finally going to start doing some speed work with my Pfitz plan. I think most beginners could benefit from having a stronger base. But as mentioned, a mix of both works for a lot of people too.

I don't think it much matters why you are running. At least a bit of unstructured speed can benefit nearly anyone. It aids in injury prevention because it strengthens your support structure and you aren't using the exact same muscles in the exact same way over and over and over. Beyond that, it adds variety which a) also aids in injury prevention and b) makes it interesting and avoiding boredom is one of the things that keeps you running. Can you get hurt by doing too much speed work? Sure. But I think far more get hurt by adding too much volume.

Short Term Goal - 17:59 5K

Medium Term Goal - 2:54:59 marathon

Long Term Goal - To have been a runner half my life (I started at age 45)

Am the only one who considers 9-10 minute fast?? If you're dead slow I'm a turtle!! Haha. I'm trying to both now - build my base more and work on speed. I want to run my 2nd 10k in oct but wnt a better time. Still haven't run longer rn a 10 k! Longer distances scare me!

What doing intervals and tempo does for me, is nothing short of changing the way i run. What i found by introducing speed into my workouts was that i needed to lengthen my stride, kick my heels to my butt, and drive the knee forward. When i do those things, i went faster. In fact, i don't have to look at my watch to know my pace anymore, but instead, if i can feel the stretch and contraction in my glutes, i know my stride is longer and i've left the realm of jogging.

A strategy to get that feeling into your repetoire is doing some moderate down-hill sprints. It allows you to stretch your stride gently with the aid of gravity adding its little pull. Only a very slight downhill is needed for these, maybe 2% to 3%.

I don't think it much matters why you are running. At least a bit of unstructured speed can benefit nearly anyone. It aids in injury prevention because it strengthens your support structure and you aren't using the exact same muscles in the exact same way over and over and over. Beyond that, it adds variety which a) also aids in injury prevention and b) makes it interesting and avoiding boredom is one of the things that keeps you running. Can you get hurt by doing too much speed work? Sure. But I think far more get hurt by adding too much volume.

IMO, I think it does matter. Someone who's running to get in shape for an explosive sport like basketball would train differently vs someone looking to eventually run an utra.

Based on the response the OP gave, health, fitness, maybe a HM the response you gave is spot on.

Am the only one who considers 9-10 minute fast?? If you're dead slow I'm a turtle!! Haha. I'm trying to both now - build my base more and work on speed. I want to run my 2nd 10k in oct but wnt a better time. Still haven't run longer rn a 10 k! Longer distances scare me!

The OP is running 9-10 minutes per kilometer which is around 15 minutes per mile.

Am the only one who considers 9-10 minute fast?? If you're dead slow I'm a turtle!! Haha. I'm trying to both now - build my base more and work on speed. I want to run my 2nd 10k in oct but wnt a better time. Still haven't run longer rn a 10 k! Longer distances scare me!

It's all relative. One person's 5k pace is another person's recovery pace. All that matters is how you're doing against yourself.

Am the only one who considers 9-10 minute fast?? If you're dead slow I'm a turtle!! Haha. I'm trying to both now - build my base more and work on speed. I want to run my 2nd 10k in oct but wnt a better time. Still haven't run longer rn a 10 k! Longer distances scare me!

The OP is running 9-10 minutes per kilometer which is around 15 minutes per mile.

Thank you for the clarification and for reminding everyone I'm a snail

If it's one or the other, than run more...gradually. You'll naturally get faster as your fitness improves. Find different courses that have hills on occasion. Short hill repeats will do wonders for your form and fitness. Add a progressive run to one of the days, where you get faster throughout the run.

The injury forum is filled with beginner runners who add speed work too soon for reasons ranging from intensity to length to not running easily enough on the other days. Once you get your mileage up to a point where you've been consistent sustaining 3 to 4 days a week of 5 or so miles each run, taking one day and doing tempo intervals or longer repeats can be fun.